Authentication method for an electronic device

ABSTRACT

The present disclosure relates to a method of authenticating a user by means of an electronic device comprising a user output interface. The present disclosure also relates to a corresponding electronic device and to a computer program product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 U.S. National Stage of InternationalApplication No. PCT/SE2019/050113, filed Feb. 11, 2019, which claimspriority to Swedish Patent Application No. 1850172-6, filed Feb. 16,2018. The disclosures of each of the above applications are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method of authenticating a user bymeans of an electronic device comprising a user output interface. Thepresent disclosure also relates to a corresponding electronic device andto a computer program product.

BACKGROUND

Various types of biometric systems are used more and more in order toprovide for increased security for accessing an electronic device,thereby providing an enhanced user convenience. In particularfingerprint sensors have been successfully integrated in such devices,for example, thanks to their small form factor, high performance anduser acceptance. Among the various available fingerprint sensingprinciples (such as capacitive, optical, thermal, ultrasonic, etc.),capacitive sensing is currently most commonly used, in particular inapplications where size and power consumption are important issues. Themost common fingerprint sensors currently used have a size e.g.corresponding to a fingertip (or smaller).

However, recently there has been a trend towards larger area fingerprintsensors. In relation to e.g. a mobile phone provided with a touch screencovering a majority of the front side of the mobile phone, such a largearea fingerprint sensor may possibly be arranged such that it may bepossible to capture a fingerprint image (of a finger of a user)essentially anywhere throughout a total surface area provided by thetouch screen.

An example of such a larger area fingerprint sensor implementation ispresented in US20150036065, specifically suggesting that the fingerprintsensor is incorporated in a display stack in the electronic device. Suchan implementation allows for further enhancements in regards tousability for a user of the electronic device, such as for example inregards to unlocking the electronic device, signing a transaction, etc.

Even though US20150036065 present an interesting approach in regards tolarge area fingerprint sensors, US20150036065 is completely silent inregards to how such an implementation possibly could be exploited foralso further enhancing the security for the user of the electronicdevice. Accordingly, there appears to room for allowing for furtherfunctionality to be implemented in regards to an electronic devicecomprising a large area fingerprint sensor, with specific focus onimproved usability and security.

SUMMARY

According to an aspect of the present disclosure, it is thereforeprovided a method of authenticating a user by means of an electronicdevice comprising a user output interface, a fingerprint sensing systemadapted to acquire fingerprint information of a user's finger and acontrol unit, wherein the method comprises the steps of presenting afirst instruction, by the user output interface, to the user forarranging a first finger at a first location with a first rotation,acquiring, by the fingerprint sensing system, a first portion of thefingerprint information, determining, by the control unit, a firstmatching level between the first portion of the fingerprint informationand a combination of a previously enrolled fingerprint template, thefirst location and the first rotation, presenting a second instruction,by the user output interface, to the user for arranging a second fingerat a second location with a second rotation, wherein at least one of thesecond finger, the second location, and the second rotation is differentfrom the first finger, the first location, and the first rotation,respectively, acquiring, by the fingerprint sensing system, a secondportion of the fingerprint information, determining, by the controlunit, a second matching level between the second portion of thefingerprint information and a combination of the fingerprint template,the second location and the second rotation, authenticating, by thecontrol unit, the user based on the first and the second matching level.

The present disclosure is based upon the realization that security maybe enhanced for an electronic device comprising a fingerprint sensingsystem by means of providing the user of the electronic device withprecise instructions on when and how to place the finger for acquisitionof fingerprint information relating to the finger of the user.

That is, in line with the present disclosure the user is presented witha first instruction of how to position his finger in relation to anactive sensing area of the fingerprint sensing system, followed by theacquisition of a first portion of the fingerprint information, such as afirst fingerprint image. Subsequently, a second instruction is presentedto the user, with a new requirement as to how the user is to positionhis finger in relation to the active sensing area of the fingerprintsensing system, and then a second portion of the fingerprint informationis to be acquired by the fingerprint sensing system, such as a secondfingerprint image.

Following the acquisition of the first as well as the second fingerprintimage the control unit comprised with the electronic device will performa determination of how well the finger was aligned with the instructionsprovided. In addition, a comparison will be performed between theacquired fingerprint images and a previously enrolled fingerprinttemplate for the user's finger(s). It should be understood that it,depending on the technology used for acquiring the fingerprint images,may be necessary to arrange/form the fingerprint template to berotationally dependent in relation to the active sensing area of thefingerprint sensing system. That is, some fingerprint sensingtechnologies will generate rotationally non-invariant fingerprintimages, meaning that the fingerprint images will change depending on therotation of the finger in relation to the active sensing area of thefingerprint sensing system. Thus, this may in some implementations makeit a desire to form the fingerprint template for different rotations ofthe finger.

An advantage with the present disclosure is that there is a possibilityof introducing unpredictability functionality when verifying the user ofthe electronic device.

That is, the user must not only have the correct fingerprint (i.e. tosuccessfully be compared to the previously enrolled fingerprinttemplate), rather also the positioning of the finger in relation to theactive sensing area of the fingerprint sensing system must be correct,or at least within an adequate level of matching (matching level abovethe predetermined threshold).

Accordingly, it is desirable to allow the instructions to be somewhatunpredictable to the user of the electronic device. That is, rather thanallowing the first and the second instruction to be the same at eachtime the user is to be verified, the first and the second instructionmay possibly be selected somewhat at random or with a pattern/order thatis non-expected for the user. Thus, the user will not in beforehand knowhow to position the finger at the active sensing area of the fingerprintsensing system which in turn will reduce the possibility of spoofing theverification process. It may in also, in an alternative embodiment, bepossible to allow the user to select the pattern/order, e.g. where theuser is to place his finger.

In an embodiment of the present disclosure the first finger is the sameas the second finger, and the second instruction is presentedsubsequently the first instruction after a predetermined time period.Thus, the user may for example first be instructed to position his rightindex finger at a first rotation and then secondly be instructed topresent the same finger at a second rotation. The second instruction ispreferably presented shortly after the first instruction, such as withina five second time frame. As will be apparent, this will further reducethe risk of spoofing of the verification process due to the limited timeavailable for an imposter to rearrange the fingers in relation to thefirst and the second instruction. It may in some embodiments bepreferred to presenting, by the user output interface, informationrelating to a reminder of the predetermined time period.

In an alternative embodiment the first finger is different from thesecond finger, the first and the second instruction are presentedessentially simultaneously, and the first and the second portion of thefingerprint information are acquired essentially simultaneously. Thatis, rather than applying a single finger approach the user may bepresented with both the first and the second instruction simultaneously,and the user is then requested to simultaneously position the first andthe second finger at the active sensing area of the fingerprint sensingsystem.

In an embodiment of the present disclosure, the user output interfacecomprises a display screen having a functional area and the fingerprintsensing system is adapted to acquire fingerprint information of theuser's finger within an active sensing area coinciding with at least amajority of the functional area for the display screen. Such afingerprint sensing system may for example be implemented usingultrasonic technology, where for example a plurality of ultrasonictransducers is to be arranged in the vicinity of a circumference of thedisplay screen.

Preferably, the active sensing area is divided into a plurality ofdifferent “zones”. The zones may be seen as adjacently arranged e.g.rectangular shaped areas arranged adjacently to each other. Each of thezones may for example be used in conjunction with the acquisition offingerprint information. Preferably, the first and the second portion ofthe fingerprint information are acquired at a first and a second zone ofthe plurality of zones. In addition, the first instruction and thesecond instruction may for example be presented within a portion of thedisplay screen corresponding to the first and a second zone.

Generally, the concept according to the present disclosure isincreasingly advantageous when used in relation to so called large areafingerprint sensors, having an active sensing area covering a majorportion of e.g. an area of the display unit (or in some cases touchscreen). However, the concept according to the present disclosure mayalso be useful in relation to smaller fingerprint sensors, such ashaving a functional area only covering a minor portion of the displayunit.

The fingerprint sensing means may, as indicated above, be implementedusing any kind of currently or future fingerprint sensing principles,including for example capacitive, optical, thermal or ultrasonic sensingtechnology. Within the context of the present disclosure, the expression“fingerprint information of a finger of the user” should be interpretedbroadly and to include both a regular “visual image” of a fingerprint ofa finger as well as a set of measurements relating to the finger whenacquired using the fingerprint sensor. A plurality of fingerprint imagesmay be subsequently acquired and fused together, where the resultinginformation is used as an input for determining the sets of features.

In an alternative embodiment, the fingerprint sensing means isconfigured to allow the fingerprint information of the user to beacquired throughout a majority of an area covered by the display screen.

In an embodiment of the present disclosure, the electronic device is amobile phone, a tablet a laptop, and/or possibly a large areainteractive screen, etc. The biometric sensor arrangements may forexample be used by the user to unlock the electronic device, signing atransaction, etc.

According to the present disclosure, the control unit is preferably anASIC, a microprocessor or any other type of computing device forcontrolling the operation of the biometric sensor arrangements. As such,the control unit may form an integral part of the biometric sensorarrangements. It may also be possible to use more than a single controlunit. However, the control unit may also be a general control unitcomprised with the electronic device, for example configured forcontrolling the overall operation of the electronic device.

According to another aspect of the present disclosure, there is providedan electronic device, comprising a user output interface, a fingerprintsensing system adapted to acquire fingerprint information of a user'sfinger, and a control unit, wherein the control unit is adapted topresent, by the user output interface, a first instruction to the userfor arranging a first finger at a first location with a first rotation,acquire, by the fingerprint sensing system, a first portion of thefingerprint information, determine a first matching level between thefirst portion of the fingerprint information and a combination of apreviously enrolled fingerprint template, the first location and thefirst rotation, present, by the user output interface, a secondinstruction to the user for arranging a second finger at a secondlocation with a second rotation, wherein at least one of the secondfinger, the second location, and the second rotation is different fromthe first finger, the first location, and the first rotation,respectively, acquire, by the fingerprint sensing system, a secondportion of the fingerprint information, determine a second matchinglevel between the second portion of the fingerprint information and acombination of the fingerprint template, the second location and thesecond rotation, authenticate the user based on the first and the secondmatching level. This aspect of the present disclosure provides similaradvantages as discussed above in relation to the previous aspect of thepresent disclosure.

According to a further aspect of the present disclosure, there isprovided a computer program product comprising a non-transitory computerreadable medium having stored thereon computer program means forauthenticating a user by means of an electronic device comprising a useroutput interface, a fingerprint sensing system adapted to acquirefingerprint information of a user's finger and a control unit, whereinthe computer program product comprises code for presenting a firstinstruction, by the user output interface, to the user for arranging afirst finger at a first location with a first rotation, code foracquiring, by the fingerprint sensing system, a first portion of thefingerprint information, code for determining, by the control unit, afirst matching level between the first portion of the fingerprintinformation and a combination of a previously enrolled fingerprinttemplate, the first location and the first rotation, code for presentinga second instruction, by the user output interface, to the user forarranging a second finger at a second location with a second rotation,wherein at least one of the second finger, the second location, and thesecond rotation is different from the first finger, the first location,and the first rotation, respectively, code for acquiring, by thefingerprint sensing system, a second portion of the fingerprintinformation, code for determining, by the control unit, a secondmatching level between the second portion of the fingerprint informationand a combination of the fingerprint template, the second location andthe second rotation, code for authenticating, by the control unit, theuser based on the first and the second matching level. Also this aspectof the present disclosure provides similar advantages as discussed abovein relation to the previous aspects of the present disclosure.

As mentioned above, the control unit is preferably an ASIC, amicroprocessor or any other type of computing device. Similarly, asoftware executed by the control unit for operating the presentlydisclosed functionality may be stored on a computer readable medium,being any type of memory device, including one of a removablenonvolatile random access memory, a hard disk drive, a floppy disk, aCD-ROM, a DVD-ROM, a USB memory, an SD memory card, or a similarcomputer readable medium known in the art.

Further features of, and advantages with, the present disclosure willbecome apparent when studying the appended claims and the followingdescription. The skilled addressee realize that different features ofthe present disclosure may be combined to create embodiments other thanthose described in the following, without departing from the scope ofthe present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects of the present disclosure, including its particularfeatures and advantages, will be readily understood from the followingdetailed description and the accompanying drawings, in which:

FIG. 1 is an illustration of an exemplary electronic device comprising afingerprint sensor according to an embodiment of the present disclosure,the electronic device presented in the form of a mobile phone;

FIGS. 2A-2C illustrates possible steps taken by a user in operating theelectronic device according to a first embodiment of the presentdisclosure,

FIGS. 3A-3C illustrates possible steps taken by the user in operatingthe electronic device according to a second embodiment of the presentdisclosure and

FIG. 4 is a flowchart schematically illustrating the operation as ispresented in FIGS. 2A-2C and FIGS. 3A-3C.

DETAILED DESCRIPTION

The present disclosure will now be described more fully hereinafter withreference to the accompanying drawings, in which currently preferredembodiments of the present disclosure are shown. This present disclosuremay, however, be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided for thoroughness and completeness, and fullyconvey the scope of the present disclosure to the skilled user. Likereference characters refer to like elements throughout.

Embodiments described herein provide one or more fingerprint sensorsthat are incorporated with an electronic device. The fingerprint sensorcan employ any type of sensing technology, including, but not limitedto, capacitive, piezoelectric, and ultrasonic sensing technologies. Inone embodiment, a single fingerprint can be captured at one time at asingle pre-defined fixed location on a display. In another embodiment, asingle fingerprint can be acquired at one time at any location on adisplay. In other embodiments, multiple touches on the display can beacquired substantially simultaneously where only one fingerprint iscaptured at a time or where all of the fingerprints are acquired at thesame time.

Directional terminology, such as “top”, “bottom”, “front”, “back”,“leading”, “trailing”, etc., is used with reference to the orientationof the Fig(s) being described. Because components of embodimentsdescribed herein can be positioned in a number of differentorientations, the directional terminology is used for purposes ofillustration only and is in no way limiting. When used in conjunctionwith layers of a display or device, the directional terminology isintended to be construed broadly.

Turning now to the drawings and to FIG. 1 in particular, there isschematically illustrated an example embodiment of the electronic deviceaccording to the present disclosure, in the form of a mobile phone 100with an integrated fingerprint sensor 102 and a display unit 104comprising a touch screen 106. In this embodiment, the fingerprintsensor 102 and the display unit 104/touch screen 106 are togetherarranged at the front side of the mobile phone 100. The fingerprintsensor 102 may, for example, be used for unlocking the mobile phone 100and/or for authorizing transactions carried out using the mobile phone,etc.

In the example presented in FIG. 1, the fingerprint sensor isimplemented to apply ultrasonic technology to acquire a fingerprintimage of a finger of a user. The fingerprint sensor 102 may inaccordance to the present disclosure for example be implemented using anultrasonic transducer device including e.g. a first piezoelectricelement and a second piezoelectric element, each having first and secondtransducer electrodes that are both connectable from one side of theultrasonic transducer device. The mobile phone 100 further comprises acontrol unit (not explicitly shown) adapted for processing fingerprintimage data acquired using the fingerprint sensor 102.

It should be understood that the concept as is provided in line with thepresent disclosure also or instead may be used in relation tofingerprint sensors employing different technologies, such as e.g.capacitive, optical, etc. as has been mentioned above. Generally, theconcept according to the present disclosure is increasingly advantageouswhen used in relation to so called large area fingerprint sensors,having a functional (or active sensing) area covering a major portion ofe.g. an area of the touch screen 106. However, the concept according tothe present disclosure may also be useful in relation to smallerfingerprint sensors, such as having a functional area only covering aminor portion of the touch screen 106.

As is schematically indicated in FIG. 1, the fingerprint sensor 102comprises a first ultrasonic transducer array 106, a second ultrasonictransducer array 108, where the control unit is connected to the first106 and second 108 ultrasonic transducer arrays.

The first ultrasonic transducer array 106 and the second ultrasonictransducer array 108 are both acoustically coupled to a device member,such as a glass cover 112 of the display unit 104/touch screen 106. Theuser touch is indicated by the thumb 114 in FIG. 1.

When the fingerprint sensor 102 is in operation, the control unit 110controls one or several piezoelectric element(s) comprised in at leastone of the first 106 and the second 108 ultrasonic transducer arrays totransmit an acoustic transmit signal. Further, the control unit controlsat least one of the first 106 and the second 108 ultrasonic transducerarrays to receive acoustic interaction signals, indicated by the dashedarrows in FIG. 1. The acoustic interaction signals are indicative ofinteractions between the transmit signal and the interface between thecover glass 112 and the skin of the user (thumb 114). The acousticinteraction signals may then be transformed to electrical signals by thereceiving piezoelectric elements in the first 106 and/or second 108ultrasonic transducer arrays, and the electrical signals are processedby the control unit to provide a representation of the fingerprint ofthe user.

It should be understood that the “representation” of the fingerprint ofthe user may be any information extracted based on the received acousticinteraction signals, which is useful for assessing the similaritybetween fingerprint representations acquired at different times. Forinstance, the representation may comprise descriptions of fingerprintfeatures (such as so-called minutiae) and information about thepositional relationship between the fingerprint features. Alternatively,the representation may be a fingerprint image, or a compressed versionof the fingerprint image. For example, the image may be binarized and/orskeletonized. Moreover, the fingerprint representation may be theabove-mentioned impulse response representation.

Preferably and as is apparent for the skilled person, the mobile phone100 shown in FIG. 1 further comprises a first antenna for WLAN/Wi-Ficommunication, a second antenna for telecommunication communication, amicrophone, a speaker, and a phone control unit. Further hardwareelements are of course possibly comprised with the mobile phone. Itshould furthermore be noted that the present disclosure may beapplicable in relation to any other type of electronic device, such as alaptop, a remote control, a tablet, computer, IoT/Machine typecommunication device, or any other type of present or future similarlyconfigured device.

Turning now to FIGS. 2A-2C and FIG. 4, illustrating a first exemplaryoperation of the mobile phone 100 in conjunction with the presentdisclosure. The first exemplary operation is provided in relation to a“one finger” authentication, as will be elaborated below.

Specifically, in FIG. 2A it is shown how the user is presented with afirst instruction at the display unit 104. The instruction providedthrough a graphical user interface (GUI) 202 illustrated at the displayunit 104. The GUI 202 shows in the exemplary implementation a pluralityof “zones” (or areas) in the illustration provided in a matrix formationcomprising six zones denoted as 204, 206, 208, 210, 212 and 214. It mayof course be possible to allow the GUI 202 to present more or less thansix zones.

The first instruction is presented, S1, within the zone 204(corresponding to the first location as defined above), conceptuallyillustrated as a fingerprint arranged with a first rotation as comparedto a possible coordinate system of the fingerprint sensor 102. In FIG.2A the user is explicitly requested to position his left index finger atzone 204. In parallel to the instruction presented within the GUI 202,the user is given an indication of how much time he has for completingthe positioning of the finger at the first location. The time indicationmay for example be illustrated using a “time bar” 216 as exemplified.

Once the user has positioned his finger at the first location/zone 204,the control unit will acquire, S2, using the fingerprint sensor 102first portion of the fingerprint information (e.g. a first partialfingerprint of the finger of the user). The control unit willsubsequently process the first portion of the fingerprint informationfor determining, S3, a first matching level between the first portion ofthe fingerprint information and a previously enrolled fingerprinttemplate (for the same finger of the user), further dependent on how thefinger was rotated. That is, in a previous operation of the mobile phone100, the finger of the user has been enrolled though an enrollmentscheme, resulting in a fingerprint template that may be used forauthenticating the user.

It should be understood that the enrollment scheme may differ and may bedependent on the technology used for acquiring the fingerprintinformation (e.g. partial fingerprint). Some fingerprint sensingtechnologies may, as indicated above, be rotationally dependent, meaningthat the rotation of the finger in relation to the mentioned coordinatesystem for the fingerprint sensor 102 is of high interest. That is,different rotation of the finger in relation to the coordinate systemmay in such implementation give different results (within limits). Thus,once the user is again instructed to position his finger with a specificrotation at the specific location (zone), the actual rotation willaffect the matching process. Thus, in such an implementation, in casethe user is not following the instruction to positon the finger with aspecific rotation, the matching will (likely) be unsuccessful, meaningthat the matching level typically will be low.

Other types of technology used for fingerprint sensing may not bedependent on the rotation of the finger in relation to the coordinatesystem of the fingerprint sensor. However, it may be possible (and insome embodiments desirable) to e.g. make use of the touch screen 106 fordetermining how the user is rotating his finger. Accordingly, thisconcept may thus be used e.g. in the matching process for ensuring theuser is correctly rotating his finger when the fingerprint informationis to be acquired.

Subsequently, the user may be presented, S4, with a second instructionto arrange his finger at or adjacently to the surface of the fingerprintsensor 102. In the illustration provided in FIG. 2B the user is nowrequested to present the same finger as was previously requested at zone210, i.e. not at the same location as was previously requested inrelation to the first instruction, with a second rotation. As may beseen in FIG. 2B, the second rotation (in comparison to the coordinatesystem of the fingerprint sensor 102) of the finger is differentcompared to the first rotation. Arranging the finger at differentrotations (for subsequently acquired portions of fingerprintinformation) may allow for a reduced possibility to spoof theauthentication process.

It should be understood that the user may be requested to use differentfingers in relation to the first and the second instruction provided atthe GUI 202.

In FIG. 2B it is also optionally presented an indication of that thefirst portion of the fingerprint information has been acquired at thefirst location, i.e. zone 204, e.g. using a check mark 218.

Again, the control unit operates the fingerprint sensor 102 to acquire,S5, fingerprint information, now a second portion of the fingerprintinformation. Furthermore, the control unit determines, S6, a secondmatching level between the second portion of the fingerprint informationand previously enrolled fingerprint template, further dependent on therotation of the finger. As previously illustrated, the user may again begiven an indication of how much time he has to complete the positioningof his finger at the second position with the second rotation. In casethe user is not positioning his finger correctly within the dictatedtime frame, the authentication process may be “stopped” and theauthentication of the user refused.

Subsequently, as shown in FIG. 2C, the control unit will authenticate,S7, the user based on the first and the second matching level. Forexample, it may be possible to allow the authentication to only besuccessful in case both of the first and the second matching level isabove a first and a second (e.g. similar) threshold, respectively. Inanother example it may be possible to combine the first and the secondmatching level (addition, multiplication) and then compare the result toa “common” threshold. Such an implementation may allow for one of theacquired portion of fingerprint information to be “slightly inferior” towhat is normally desired, however in case the second portion of thefingerprint information is slightly above what is normally desired thenthe combination of the two may still be enough for exceeding thecombined threshold. Other implementations for e.g. correlating the firstand the second matching level with one or a plurality of thresholds arepossible and within the scope of the present disclosure.

FIGS. 3A-3C provides a second exemplary embodiment of operation of themobile phone 100 in line with the concept according to the presentdisclosure. As compared to the first exemplary embodiment as shown inFIGS. 2A-2C, the second exemplary embodiment shows a “two finger”authentication, as will be elaborated below. Specifically, in FIGS.3A-3B the GUI 202 is illustrated to comprise three zones 302, 304 and306.

To start with, the user will be provided with a first instruction topresent his two index fingers at a first location with a first rotation,specifically within zone 306. The instruction is again provided using astylistic illustration of a first and a second fingerprint representinghow and where the user is to position his fingers. Again, a firstmatching level is to be determined.

In FIG. 3B the user is now requested to position his fingers at a secondlocation, specifically within zone 302 with a specific rotation.However, as compared to FIG. 3A where the index fingers were to bepresented at the fingerprint sensor 102, the user is now requested toposition his thumbs (i.e. both left and right) within zone 302. As wouldbe apparent, not previously knowing which finger to position at whatlocation will greatly reduce the possibility of spoofing theauthentication process provided in line with the present disclosure.

It should be understood that any combination of fingers may be requestedto be position at the fingerprint sensor 102. That is, e.g. two or evenfurther fingers from the same hand may be requested to be positioned atthe fingerprint sensor 102, or e.g. two fingers from one hand and onefinger from the other hand.

Once the second portion of the fingerprint information has beenacquired, the second matching level is to be determined. In line withthe above discussion in relation to FIGS. 2A-2C, the authentication, asexemplified in FIG. 3C, will subsequently be based on the first and thesecond matching level, possibly in combination or compared separately.

The control functionality of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a machine, the machine properly views theconnection as a machine-readable medium. Thus, any such connection isproperly termed a machine-readable medium. Combinations of the above arealso included within the scope of machine-readable media.Machine-executable instructions include, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing machines to perform a certain function orgroup of functions.

Although the figures may show a sequence the order of the steps maydiffer from what is depicted. Also two or more steps may be performedconcurrently or with partial concurrence. Such variation will depend onthe software and hardware systems chosen and on designer choice. Allsuch variations are within the scope of the disclosure. Likewise,software implementations could be accomplished with standard programmingtechniques with rule based logic and other logic to accomplish thevarious connection steps, processing steps, comparison steps anddecision steps. Additionally, even though the present disclosure hasbeen described with reference to specific exemplifying embodimentsthereof, many different alterations, modifications and the like willbecome apparent for those skilled in the art.

In addition, variations to the disclosed embodiments can be understoodand effected by the skilled addressee in practicing the claimed presentdisclosure, from a study of the drawings, the disclosure, and theappended claims. Furthermore, in the claims, the word “comprising” doesnot exclude other elements or steps, and the indefinite article “a” or“an” does not exclude a plurality.

The invention claimed is:
 1. A method of authenticating a user by meansof an electronic device comprising a user output interface, afingerprint sensing system adapted to acquire fingerprint information ofa user's finger and a control unit, wherein the method comprises thesteps of: presenting a first instruction, by the user output interface,to the user for arranging a first finger at a first location with afirst rotation, acquiring, by the fingerprint sensing system, a firstportion of the fingerprint information, determining, by the controlunit, a first matching level between the first portion of thefingerprint information and a combination of a previously enrolledfingerprint template, the first location and the first rotation,presenting a second instruction, by the user output interface, to theuser for arranging a second finger at a second location with a secondrotation, wherein at least one of the second finger, the secondlocation, and the second rotation is different from the first finger,the first location, and the first rotation, respectively, acquiring, bythe fingerprint sensing system, a second portion of the fingerprintinformation, determining, by the control unit, a second matching levelbetween the second portion of the fingerprint information and acombination of the fingerprint template, the second location and thesecond rotation, authenticating, by the control unit, the user based onthe first and the second matching level.
 2. The method according toclaim 1, wherein: the first finger is the same as the second finger, andthe second instruction is presented subsequently the first instructionafter a predetermined time period.
 3. The method according to claim 2,wherein the predetermined time period is less than 5 seconds.
 4. Themethod according to claim 2, further comprising the step of: presenting,by the user output interface, a reminder of the predetermined timeperiod.
 5. The method according to claim 1, wherein: the first finger isdifferent from the second finger, the first and the second instructionare presented essentially simultaneously, and the first and the secondportion of the fingerprint information are acquired essentiallysimultaneously.
 6. The method according to claim 1, wherein the useroutput interface comprises a display screen having a functional area andthe fingerprint sensing system is adapted to acquire fingerprintinformation of the user's finger within an active sensing areacoinciding with at least a majority of the functional area for thedisplay screen.
 7. The method according to claim 6, wherein thefingerprint sensing system comprises a plurality of ultrasonictransducers in the vicinity of a circumference of the display screen. 8.The method according to claim 6, wherein the active sensing area isdivided into a plurality of zones.
 9. The method according to claim 8,wherein the first and the second portion of the fingerprint informationare acquired at a first and a second zone of the plurality of zones. 10.The method according to claim 9, wherein the first instruction and thesecond instruction are presented within a portion of the display screencorresponding to the first and the second zone.
 11. An electronicdevice, comprising: a user output interface; a fingerprint sensingsystem adapted to acquire fingerprint information of a user's finger,and a control unit, wherein the control unit is adapted to: present, bythe user output interface, a first instruction to the user for arranginga first finger at a first location with a first rotation, acquire, bythe fingerprint sensing system, a first portion of the fingerprintinformation, determine a first matching level between the first portionof the fingerprint information and a combination of a previouslyenrolled fingerprint template, the first location and the firstrotation, present, by the user output interface, a second instruction tothe user for arranging a second finger at a second location with asecond rotation, wherein at least one of the second finger, the secondlocation, and the second rotation is different from the first finger,the first location, and the first rotation, respectively, acquire, bythe fingerprint sensing system, a second portion of the fingerprintinformation, determine a second matching level between the secondportion of the fingerprint information and a combination of thefingerprint template, the second location and the second rotation,authenticate the user based on the first and the second matching level.12. The electronic device according to claim 11, wherein the user outputinterface comprises a display screen.
 13. The electronic deviceaccording to claim 12, wherein the fingerprint sensing system isconfigured to allow the fingerprint information of the user to beacquired throughout a majority of an area covered by the display screen.14. The electronic device according to claim 11, wherein the fingerprintsensing system is employing at least one of optical, thermal andultrasonic sensing technology.
 15. The electronic device according toclaim 11, wherein the electronic device is a mobile phone, a tablet or alaptop.